On 24 August 1863 the Union gunboats USS J.P. Jackson and Genesee (both sidewheel steamers) attacked Confederate Ft. Powell
at Grant’s Pass. This was an inside entrance into Mobile Bay via the sounds
along the Mississippi Coast. Ft. Powell was constructed to guard this “back
door” and prevent Union incursions via this route. It was initially named Ft.
Grant, but renamed Ft. Powell after the death of its commander, Confederate
Col. William L. Powell, commanding the defenses of lower Mobile Bay. The USN
gunboats lobbed a number of shells at the fort, but only 6-8 hit the fort or
the island it was built on. Eventually the Union warships withdrew.

A second sortie against Ft. Powell by the Union
Navy was made on 13 September 1863 by the warships Jackson, Genesee, and the
USS Calhoun (a captured blockade
runner steamer). The USN gunboats kept up a fire from 10 AM to about 4 PM.
Again only a small percentage of the shells fired actually hit the fort or its
island. In both engagements no Confederate casualties were caused by the Union Navy
gunfire and no damage was done to the fort.